The present invention relates to an orthodontic arch wire for use with orthodontic brackets mounted at about the middle of the clinical crown of each of a plurality of teeth. More particularly, the arch wire form of this invention is especially useful with tooth-mounted orthodontic brackets of the type described in U.S. Pat. No. 3,660,900, issued May 9, 1972, wherein the location of the groove is generally defined by a horizontal plane intersecting approximately the mid-point of the long axis of the clinical crown of the tooth.
Among the objectives of those specializing in orthodontia is to produce normal occlusion of teeth through relocation thereof by forces created by various forms of mechanical appliances. Such mechanical appliances have long included brackets suitable for attachment either directly to a tooth or to a band surrounding an individual tooth or a pad that is adhesively secured to an individual tooth. The brackets are conventionally formed with a rectangular groove in the outer face thereof for receipt of an arch wire. The orthodontist inserts the arch wire in the grooves of the tooth-mounted brackets and then applies what he considers to be appropriate corrective forces to each tooth by bending the arch wire on either side of an individual bracket.
More recently, various approaches have been developed to minimize the amount of time heretofore required for handbending of the orthodontic arch wire. Such approaches have involved pre-forming the arch wire with predetermined bends designed to minimize the amount of hand-bending required to produce the corrective forces considered by the arch wire designer to be necessary to attain ideal occlusion.
Typical of such pre-formed arch wires are those provided by the process disclosed in U.S. Pat. No. 2,566,414 which issued on Sept. 4, 1951. The purpose of this patented technique was to provide the orthodontist with an arch wire having a symmetry corresponding to what the inventor had determined to be an average arch so that further hand-bending would be minimized. U.S. Pat. No. 2,566,414 disclosed apparatus and a process for forming a standardized arch wire with a number of divisions of varying curvature, offset in relation to each other so as to conform to the inventor's characterization of what should constitute the proper arch symmetry of an average size set of teeth. Additionally, provision was made for pre-torquing the arch wire (1) by forming the arch wire with dies having predetermined surface inclination and (2) by rolling the arch wire in the plane of the finished arch.
Furthermore, a dental arch form has been proposed that consists of a compound curve representing a steady state of equilibrium delimited by what was calculated to be the counterbalancing force field of the tongue and of the circumoral tissues as applied at the outermost portion of each tooth. Such a dental arch form is intended to approximate the unique geometry of a closed curve having trifocal elliptic properties, with the teeth occupying only a portion of the total curve at its constricted end; see American Journal of Orthodontics, Volume 61, No. 6, pages 541-561, June, 1972.
A further arch wire form has now been discovered that exhibits unexpectedly superior results when utilized to apply corrective forces to teeth through orthodontic brackets where the brackets are located on the teeth so that the grooves lie on a plane generally extending through about the middle of the clinical crown of each tooth. More particularly, it has now been found that, with the aforementioned bracket mounting position, there is an arch wire, pre-formed from a series of unique contiguous circular segments, that substantially eliminates the need for the orthodontist to hand-bend the dental arch wire form once an appropriate size of arch form has been selected.
Thus, it is a principal object of this invention to provide a specialized dental arch wire form that is particularly suitable for use with the type of bracket disclosed in the aforementioned U.S. Pat. No. 3,660,900, when each of such brackets is applied so that the groove therein lies at about the middle of the clinical crown of the respective tooth being treated.